The extreme heat and high humidity pose risks of heat-related illnesses, particularly for vulnerable populations such as the elderly, children, and those with pre-existing health conditions. Residents in northern and central Cook, DuPage, Lake, Kane, DeKalb, Lee, Ogle, McHenry, Boone, and Winnebago counties are expected to experience the brunt of the heat. Prolonged exposure to high temperatures without adequate hydration and cooling measures could lead to heat exhaustion or heat stroke.